linuxexpert-practice-labs/labs/lpic-1/103-5-processes

LPIC-1 103.5: Creating, watching and killing processes

Job control, a tmux session that outlives your login, signalling processes by name, and finding the biggest memory users.

Before you start

The lab installs tmux if it's missing. Write answers to the files in /root/lab-answers/. Running processes don't survive a reboot, so check before you reboot.

Tasks

1. Start sleep 600, suspend it with Ctrl-Z, list it with jobs, resume it with bg, bring it back with fg, and end it with Ctrl-C. Check it yourself: jobs shows it as Stopped, then Running.
2. Start a tmux session, run top in it, detach, log out, log back in and reattach. Leave top running in the session.
3. Start sleep 1000 & three times, list them with pgrep -a sleep, and end them all with one pkill. Check it yourself: pgrep -a sleep prints nothing afterwards.
4. Use ps -eo pid,%mem,comm --sort=-%mem | head to find the five biggest memory users, and compare with top sorted by memory. Write their PIDs and names, biggest first, one per line, to /root/lab-answers/4.
5. Start a CPU-heavy loop in the background (while :; do :; done &), then run watch -d uptime and see the load average climb. Leave watch with Ctrl-C and end the loop with kill %1. Check it yourself: jobs is empty afterwards.

Hints

• Ctrl-Z, jobs, bg %1, fg %1.
• tmux, top, Ctrl-B then d to detach, tmux ls, tmux attach.
• pgrep -a, pkill sleep (or pkill -x sleep).
• In top, Shift+M sorts by memory.